The quantum internet just took a massive leap from theoretical to practical.
Qunnect and Cisco have successfully demonstrated entanglement swapping — a fundamental operation for quantum networking — across 17.6 kilometres of commercial telecom fibre running between Brooklyn and Manhattan. And they didn't just make it work. They smashed every previous record doing it.
The collaboration achieved swapping rates of over 1.7 million entangled pairs per hour locally, and 5,400 pairs per hour over deployed fibre. That's nearly 10,000 times better than previous benchmarks using similar platforms. The system maintained greater than 99% polarisation fidelity — meaning the quantum information stayed remarkably intact even through some of the noisiest, most chaotic fibre optic cables on Earth.
'Entanglement swapping is a fundamental operation in the quantum internet,' said Mehdi Namazi, Qunnect's Co-Founder and Chief Science Officer. 'Today, we not only broke the record for rate and scalability, we did so in New York City using some of the noisiest, most chaotic fibre on Earth.'
So what exactly is entanglement swapping, and why does it matter?
Quantum entanglement is the phenomenon where two particles become linked so that measuring one instantly affects the other, regardless of distance. It's the foundation of quantum communication — enabling perfectly secure encryption and, eventually, a quantum internet that could connect quantum computers worldwide.
But entanglement is fragile. Over long distances, the quantum signal degrades. Entanglement swapping solves this by acting as a kind of quantum relay — creating entanglement between distant points by linking shorter entangled segments together. Think of it as building a bridge span by span rather than trying to throw one across an entire canyon.
What makes this demonstration particularly significant is the architecture. The end nodes use room-temperature detectors, with cryogenic equipment concentrated only at the central hub. This dramatically reduces the cost of scaling the network — you don't need expensive cooling equipment at every endpoint.
The system also uses independent entanglement sources that don't require shared lasers, allowing for modular expansion. Need to add another node to the network? Just plug it in.
The demonstration ran on Qunnect's GothamQ testbed — yes, it's really called that — which threads through New York City via QTD Systems' data centre at 60 Hudson Street, one of the world's most important telecom hubs.
While a full quantum internet is still years away, this milestone proves that the core technology works reliably in real-world conditions, at commercially viable speeds, using existing fibre infrastructure. The path from laboratory curiosity to deployed infrastructure just got a lot shorter.
The future is entangled — in the best possible way. ⚛️